Weimaraner dog Maci, 8, wears a prison costume with the words" bad-dog" on the back. "She is a counter surfer. She will eat anything off the counter," said Lynne Thiel of Dundee, manager of Pet Supplies Plus and Maci's owner.
Joseph Tobianski I AnnArbor.com

Manager Lynne Thiel said this was the first year for the party, although they've held Halloween photo contests in previous years. This year, as more and more people are dressing up their pets, the store wanted to make it more personal.

Plus, sales for pet Halloween costumes were up this year, she said.

About 14.7 percent of people will dress their pets in costume this year, according to the National Retail Federation, with about $310 million spent on costumes.

Why is that? Thiel says she thinks it's because more pet owners come to view their animals as part of the family, and dressing your children up for Halloween is just something you do.

"Everybody has a different version of what their child is," she said.

Once your kids are too old to dress up, then it's the dog's turn, Thiel says, adding that her dog will be trick-or-treating right alongside her grandson this year.